With the continuous development of the communications technologies, the size of digital devices like Universal Serial Bus (USB) devices, data cards, and mobile phones is decreasing. As a result, the requirements for components of the digital devices are becoming more advanced.
Currently, to increase the flexibility and ease of use of the digital devices, a component known as a rotation axis is used in many digital devices. The most commonly used rotation axis is a metal rotation axis.
At least the following weaknesses exist in the conventional rotation axis described above: the structure of the existing metal rotation axis is complex; the size is large; and the cost is high.
The inventors have created the above body of information for the convenience of the reader and expressly disclaim all of the foregoing as prior art; the foregoing is a discussion of problems discovered and/or appreciated by the inventors, and is not an attempt to review or catalog the prior art.